1. Field of the Invention
The invention relates to a cooled stator for an electric machine with a rotating rotor or for an electric linear motor. The stator is in each case formed with a magnetic laminated core and comprises one or more flexibly deformable cooling channels, which act on the laminated core, for flowing cooling medium.
2. Description of the Related Art
DE 197 42 255 C1 discloses a housing-free three-phase machine with paraxial coolant tubes in the stator laminated core. As the coolant tubes are rigid, difficulties may arise when they are inserted in bores in the stator laminated core, in particular when there are bent paths. It is especially necessary to assemble the cooling channels in sectionalised and complex fashion from different tube portions with deflection bends, corner connection bends and similar.
A cooling jacket with a through-flow of liquid for an electric machine is known from the patent publication EP 0 829 946 A1. A tight-fitting, hose-shaped structure, which is flexible and elastic and consists of rubber or silicone, is proposed as the cooling jacket. This cooling xe2x80x9cbagxe2x80x9d/hose is not only flexible, but can also be extended considerably. This cooling jacket can therefore sit closely against surfaces of stator laminated cores of the most varied forms. Since, however, according to the known proposal, the cooling jacket is extensible and compressible in all directions, it is difficult to introduce this into narrow, paraxial or radial bores of a laminated core. This means that it is also problematic to assemble the cooling device in the stator laminated core in this case.
xe2x80x9cDEPANETxe2x80x94Bibliographische Datenxe2x80x9d (xe2x80x9cBibliographical dataxe2x80x9d) discloses a brief abstract of a Chinese patent application CN 1 264 207 according to which corrugated tubes can be inserted in the cooling device of an electric motor. However this source reference fails to reveal a more precise structure or constructional details on the arrangement of the corrugated tube.
The object of the invention is to provide a cooled stator which allows the cooling device to be rapidly and easily assembled.
In order to solve this object with regard to a stator having the features initially mentioned, the invention proposes that the one or a plurality of cooling channel(s) be formed with one or a plurality of flexible corrugated metal hose. These flexible fluid lines, which are known per se (cf. xe2x80x9cHandbuch der Metallschlxc3xa4uchexe2x80x9d (xe2x80x9cMetal hose handbookxe2x80x9d), Labhard-Verlag Konstanz 1 999/Witzenmann GmbH, Pforzheim) are distinguished by the fact that they essentially only permit movements or bends transversely to the longitudinal direction, yet cannot be compressed or accommodate movements in the longitudinal direction. The use of corrugated tubes or hose of this kind in electrical machine construction is already known from the European patent specification EP 0 035 071 B1, although only in connection with a water-cooled rotor, and in this case as a flexible intermediate member between a connecting fitting on the overhang side and a water distributing chamber.
The invention makes advantageous use of the axial rigidity of corrugated hose or tubes when assembling the cooling means in the stator to enable these to be rapidly inserted in recesses, slots or bores of the stator laminated core. On account of the flexibility, the corrugated hose can rapidly adapt to the most varied cooling channel paths. The axial rigidity enables them to be easily passed through the cooling bores in the stator laminated core and inserted. A further advantage which is obtained with the invention lies in the fact that, because the inner wall of the corrugated hose has multiple corrugations, turbulence of the cooling medium flowing therein is increased, which in turn increases the heat exchange and the heat elimination.
According to a special formation of the invention, winding slots which are provided at the stator laminated core are utilised as guide receptacles for the corrugated hose. This measure provides the advantage of the corrugated hose or the fluid flowing through them (cooling liquid or air) cooling not just the magnetic or dynamo lamination of the stator, but also the conducting windings or conductors thereof.
On account of their flexibility, the corrugated hose can be guided around corners, edges, front sides or similar of the stator and tightened at their ends. This results in an advantageous formation of the invention according to which the corrugated hose can be laid in the laminated core of the stator under tensile stress, which on the one hand increases the mechanical strength and unity of the stator and on the other augments contact between the cooling corrugated hose and the stator parts.
It is expedient to use a corrugated hose of a thermally stable, flexible material which is a good conductor of heat, with small bending radii also being possible. A corrugated hose consisting of special steel proves to be particularly suitable.
It is expedient to lay the corrugated hose in bores in the laminated core which are provided for the cooling channels in order to increase the heat transfer efficiency between the cooling channel and the stator laminated core. According to an advantageous formation of the invention, the bores which are required to draw in the corrugated hose may be filled with materials which are good conductors of heat (e.g. aluminium, soldering tin, etc.) in order to further increase thermal conductivity. Zinc, lead or a plastics material may also be used as casting materials on account of their good heat-conductive properties.
Casting with a heat-conductive material is also suitable for corrugated hose which are laid in winding slots. If, however, direct contact between the corrugated hose and the winding is to be avoided, e.g. for reasons of safety and reliability, it is more expedient to lay the hose in the bores. The corrugated hose may also have greater diameters in such a case. The bores for the corrugated hose may extend axially, paraxially, radially and, in principle, at any conceivable angle to the centre axis or rotational axis and with any bend corresponding to the smallest possible bending radius of the corrugated hose.
The use of the stator cooling device according to the invention both with electric linear motors and with all known, electric rotary motors of different designs is possible within the scope of the general inventive concept. Air, water and all other media which are known for cooling purposes are suitable as cooling medium. The use according to the invention of the corrugated hose always leads to very good assembly possibilities and a resulting significant saving of time. The corrugated hose end of the stator cooling system can be connected to external cooling fluid circuits and supply devices by means of connecting elements which are known per se, such as plug-in nipples, hose coupling, adapters and the like.
A contributory factor in this respect lies in an advantageous formation of the invention according to whichxe2x80x94in the case of electric rotary motorsxe2x80x94the corrugated hose are laid and/or bent in the region of stator front sides or any end shields which are to be attached such that meander-like windings are produced. The curve formation, which is linked with this, for the cooling medium flow path promotes the above-mentioned turbulence. In the case of electric linear motors a formation of the invention in which a plurality of corrugated hose or corrugated hose portions extending parallel and transversely to the stator longitudinal direction are connected together by bent portions corresponds to this.